The present invention relates to a defect inspection apparatus for inspecting an object for a defect.
In macro inspection for inspecting a surface of an object such as a patterned wafer for a defect in a semiconductor fabrication plant, intense light is shot at the object surface from obliquely. The operator observes the state of scattered light or diffracted light by visual inspection to judge whether there is a defect or not, its type and the like. However, individual operators vary in inspection ability. Further, operators may miss detecting a defect. Therefore, it is difficult to secure stable quality. Furthermore, the operator comes close to the object, contaminating the object. This creates a great obstacle in improving the product yield. Accordingly, a defect inspection apparatus for automatically inspecting an object for a defect by taking an image of its surface and processing the image has been proposed.
However, defect inspection relying on image processing of related art is intended to inspect for a defect by a logical decision in which various filters and threshold processing are combined. Various defect types are produced at each fabrication step of the object. It is difficult to classify and detect the defect types if only the combinations of various filters and standardized threshold processing are used.